Electron discharge device



May 23, 1939. a. LIEBICH ELECTRON DISCHARGE DEVICE Filed Aug. 18 1936 I'l'l'l l l l P-i l l l l l INVENTOR GEORG LIEB l CH MMwr ATTORNEY UNITED STATES Patented May 23, 1939 2,159,767 PATENT OFFICE.

ELEGTRO N DISCHARGE: DEVICE Georg Liebich, Berlin, Germany, assignor to Tele- Germany funken Gesellschaft fiir Drahtlose Telegraphie m. b. H., Berlin, Germany, a corporation of Application August 18, 1936, Serial No. 96,577 In Germany August 19, 1935 8 Claims.

, i This invention relates to gas discharge tubes having an incandescent cathode as the electron source and especially to improvements for insuring stability and uniformity of operation of such tubes.

, Such tubes sometimes have the disadvantage j that the voltage drop of the gas discharge path changes owing to exterior influences. When using rare gases, such variation may take place because of gas consumption, and when using mercury vapor there may occur still much greater f variations due to the dependence of the vapor pressure upon temperature.

, It is the principal object of my invention to provide a gas tube which is stable, and exhibits uniform characteristics during operation. According to the invention, use is made of the fact that the voltage drop not only depends upon *the gas or vapor density, but also upon the num- 0 ber of charge carriers produced per unit time.

In accordance with the invention, means are therefore provided which in proportion to the inner resistance, i. e., to the gas current of the l r tube, oppose any change in voltage drop in the gas discharge, and thus compensate for such changes. 1 1 This can be carried out in three different ways.

1 First, the filament temperature can be increased,

thereby enhancing the emission; second, an in- 3 creasein the ionization in the gas chamber can beeficcted; third, the voltage at an electrode for instance that of the anode can be increased,

a The novel features which I believe to be characteristic of my invention are set forth with parwticularity in the appended claims, but the invenftion itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which:

Figure 1 is a schematic diagram of a gas tube and its associated circuit made according to my invention, and Figure 2 is a modification of Fig- ,ure 1. i

,1 Figure 1 shows a tubeand circuit employing a I method of compensation byincreasing the tem- 'perature of the cathode. Obviously the invention is not limited tothis example. A gas filled tube :eis provided with an envelope I, containing the t ,heater 2, cathode 3, accelerationgrid 4, control 1 a grid 1, and anode 8. The gas discharge is main-. utained between cathode 3 and the discharge grid electrode 4 which is connected to the positive .]pole of the heating circuit. The battery 5 sup- :wplies the voltage for both circuits, i. e., for the heating circuit as well as for the discharge cur- 55 rent, that is the so-called gas current. Both have 3 a common resistor 6 for the control. If the inner resistance of the gas paths increases, i. e., if thegascurrent decreases, then the voltage at the filament'increases, and hence the tempera- :ture and the emission. This is explained by the ondary increase in the emission, so that theworking point of the tube remains the same. Obviously this is not the case with a pure ohmic resistor. The invention is applicable to all cases where the variationin the resistance of the gas path is automatically so compensated by exterior influences that the; cathodic functions of the entire gas path relative tothe other electrodes are maintained constant or at least approximately constant.

A circuit and tube of modified form are shown in Figure 2. The numbers 1-8 designate the same elements as in Figure 1. But here the resistor 6 is no longer common to both circuits, and together with a second battery 9 it is inserted in the gas current circuit. longer influences the heating but produces an acceleration potential at grid 4 proportional to the increase inthe gas current resistance. The auxiliary electrode ll] serves for maintaining constant the potential of the entire gas cathode relative to the other electrodes independent of the variations at grid 4. Where such necessity does not exist the auxiliary electrode may of course be omitted. As in the aforementioned method also in this case in place of the purely ohmic control, a resistance having a special characteristic may be employed, or simply a relay having a corresponding action.

With a constant voltage applied to the grid II] with respectto the cathode and anode, the field I and the-anode 8 and may also be considered as the source of electrons for the tube. If the current between the cathode 3 and grid 4 decreases due to increase in the resistance of the gas discharge paths between cathode 3 and grid 4, the

voltage on grid 4 increases as above described to maintain the current conditions the same; This change has substantially no efiect on the field distribution between grid [0 andanode 8. Under extreme conditions if current between the cathode and the grid increases considerably and A corresponding action takes Consequently it no if the grid 10 were not present the current to the anode would increase for given control grid and anode voltages, but with the grid l0 present, however, acting as a blocking grid the current to the anode would be unaffected except for those changes induced by the control grid 7. ,Thus the grid l0 cooperates with the grid 4 to maintain stabilized conditions in the tube.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention can be employed, it will be apparent that my-invention is byno meanslimited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims. 7

What is claimed to be new is:

1. The method of operating a gas discharge tube having a thermionic cathode electrode, a discharge grid electrode, a control electrode, and an anode electrode, and comprising applying a voltage to said tube to establish a gas discharge between the thermionic cathode electrode and discharge grid electrode, utilizing variations in the internal resistance of the gas discharge path to control the voltage applied to said tube and impressing the resulting voltage between said thermionic cathode electrode and said discharge grid electrode to, maintain the current to the anode substantially constant.

2. The method of operating a gas discharge tube having a thermionic cathode electrode, a discharge grid electrode, a control electrode, and an anode electrode, and comprising applying a voltage between said cathode electrode and the discharge grid electrode to establish a gas discharge between said cathode electrode and discharge grid electrode, utilizing variations in the internal resistance of the gas discharge path to control the voltage applied to said tube to vary the voltage applied to the cathode electrode whereby its temperature and emission are varied in response to variations in the inner resistance of the gas discharge path to maintain the current to the anode substantially constant.

3. The method of operating a gas discharge tube having a thermionic cathode electrode, a

discharge grid electrode, a control electrode, and an anode electrode, and comprising applying a voltage to said tube to establish a gas discharge between said cathode electrode and discharge grid electrode, utilizing variations in the internal resistance of the gas discharge path to control the voltage applied to said tube to vary the volt-* age impressed between the cathode and said discharge grid electrode wherebythe ionization of voltage to said tube to establish a gas discharge between said cathode and discharge electrode, utilizing variations in the internal resistance of the gas discharge path to control the voltage impressed between said cathode and said discharge electrode in said gas discharge tube to maintain the current to the anode substantially constant.

5. In combination a gas discharge tube having an envelope having a gaseous filling and containing a thermionic cathode, a discharge grid elec trode, acontrol electrode, and an anode electrode, a source of voltage supply for heating said cathode and for providing a gas discharge between said cathode and the discharge grid electrode, a resistance in series with said voltage supply and a connection between said discharge grid electrode and said resistor, said resistor being connected between the positive side of the source of voltage supply and said discharge grid electrode whereby variations in the internal resistance of said gas discharge path will vary the voltage between said cathode and said discharge grid electrode to maintain the anode current substantially constant.

6. In combination a gas discharge tube having a cathode and a heater'therefor, a discharge grid electrode, a control grid electrode, and an anode, and a source of voltage supply for heating said heater and for providing a gas discharge between said cathode and discharge grid electrode, and a resistor in series with said voltage supply and connected between the positive side of said source of voltage supply and said discharge grid electrode whereby variations in the internal resistance of the gas discharge path will vary the voltage applied to said heater to vary the emission from said cathode.

'7. In combination a gas discharge tube having an envelope containing a gaseous medium, a cathode, a heater for said cathode, a discharge grid electrode, a control grid, and an anode, and a source of voltage connected between the cathode and the discharge electrode, the negative side of said source of voltage being connected to the cathode and a resistor in series with said source of, voltage and said discharge grid electrode, said resistor being connected between the positive side of said source of voltage and the discharge electrode whereby variations in the internal resistance of the gas discharge grid path will vary the voltage applied to said discharge electrode to compensate for the variations in the ionization between the cathode and the discharge grid electrode.

8. In combination a gas discharge tube having an envelope containing a gaseous medium, a cathode, a heater for said cathode, a discharge grid electrode, a control grid, and an anode, and a source of voltage connected between the oathode and the discharge electrode, the negative side of said source of voltage being connected to said cathode and a resistor in series with said source of voltage and said discharge gridelectrode, said resistor being connected between the positive side of said source of voltage and said discharge grid electrodewherebyvariations in the internal resistance of the gas discharge path will vary the voltage applied to said discharge grid electrode to compensate for the variations in the ionization between the cathode and the discharge grid electrode, and a grid electrode between the control electrode and said discharge grid electrode,

for maintaining the potential of the electrodes providing the gas discharge'constantwith respect to the other electrodes independent of the variations of the voltage on the discharge grid electrode.

GEORG LIEBICH. 

